stellar-populations

The Milky Way is a barred spiral galaxy with roughly 200 to 400 billion stars. Its disk, central bar, bulge, stellar halo, and dark matter halo are mapped from the inside by Gaia and radio surveys. At the center sits Sagittarius A*, a black hole of about 4.3 million solar masses, imaged by the Event Horizon Telescope in 2022. The Sun orbits about 26,000 to 27,000 light-years out, completing a lap in roughly 200 to 230 million years.

Globular clusters are the oldest and densest stellar systems in the universe — spherical swarms of hundreds of thousands of stars bound together for billions of years. Here's how they form, what they reveal about galactic history, and why they remain one of astronomy's most productive laboratories.